Radiography is an imaging technique that uses X-rays to view inner structure of non-uniformly composed material, such as, for example, a human body. By projecting a beam of X-rays produced by an X-ray source at an object, an image of the object can be developed that clearly displays areas of differing density and composition. Based upon the density and composition of the differing areas of the object, some portion of the projected X-rays is absorbed by the object. The X-rays that pass through are then captured behind the object by a detector, a film sensitive to X-rays, which will create a two-dimensional representation of the object's structures.
Computed radiography (CR) is one form of radiography and uses similar equipment to conventional radiography except that in place of film to create an image, an imaging plate formed of a photostimulable phosphor is used. The imaging plate is generally housed in a special cassette, which can be flexible. The cassette is placed under the object to be examined, or otherwise on the opposite side of the object from an X-ray source, and the X-ray exposure is performed. This forms a latent image in the phosphor. The imaging plate is then passed through a laser scanner or other computed radiography (CR) scanner. The CR scanner reads and digitizes the latent image. Unlike conventional X-ray film, the latent image on a CR imaging plate can be erased following a read, making it ready for reuse. Throughout the remainder of this document, the terms “film” and “plate” are used interchangeably to refer to CR imaging plates.
CR scanners often use standard film sizes, e.g., 8″×10″ (˜20 cm×˜25 cm) or 14″×17″ (˜35.5 cm×˜43 cm). However, CR scanners are not restricted to these sizes. Particularly for industrial applications such as weld inspection, plates can be, e.g., 2″ to 4″ (˜5-10 cm) wide and up to, e.g., 36″ (˜91 cm) long. Such plates can be wrapped around, e.g., a welded pipe joint, and the X-ray source can be placed inside the pipe or to the side of the pipe for exposure. Other commercial and industrial plates have small sizes for imaging small objects such as small castings.
A CR latent image can last several weeks without substantial degradation. In some situations, therefore, multiple CR plates are exposed to X-rays in a batch, and then the plates are read in a batch. This permits imaging objects in harsh environments such as northern Alaska without requiring the CR scanner be operated in the harsh environment. CR plates can be exposed in situ, and reading can be performed using a CR scanner at a separate location. Accordingly, in batch processing, there is an ongoing need for ways of permitting many plates to be scanned at once to reduce the total time required to scan the entire batch. There is also a continuing need for ways of reducing total time in the presence of plates of various sizes and aspect ratios.
The discussion above is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter.